Thank you for reading my question.
I have attached the (very old 80’s) scematics with optocouplers on the left.
They are all fed by the same 5V source, in this case my arduino 5v output.
Now I want to switch them with digital ports on the Arduino, but it’s kind of the other way around…
I can set the ports on OUTPUT LOW to make them ‘ground’ and open up.
But can I set them OUTPUT HIGH without destroying anything?
Or do I have to use INPUT LOW to disconnect it, so switch between output low and input low.
If you have any advice on this… thank you very much!